GB394372A - Improvements in and relating to electric motor speed control systems - Google Patents

Abstract

394,372. Maintaining defined speeds of motors. BRITISH THOMSON-HOUSTON CO., Ltd., Crown House, Aldwych, London.-(Assignees of Thompson, L. W. ; 53, Baker Avenue, Schenectady, New York, and Horstkotte, E. H. ; 1336, West 9th Street, Erie, Pennsylvania, both in U.S.A.) Dec. 16, 1931, No. 34876. Convention date, Dec. 16, 1930. [Class 38 (iii)] Each working motor 10 is maintained at a speed proportional to a motor 74, by deriving from a device 57 an alternating current of a frequency proportional to the speed of the working motor and comparing this derived current in a device 62 with a current similarly derived from a device 59 driven by the motor 74, the resultant movement of the device 62 being used to vary the resistance of a carbon pile 82 in series with the field 27 of the motor 10. All the motors are supplied on the Ward-Leonard principle from a generator 18, the voltage of which is regulated by rheostat 42 operated by a pilot motor 47 under the control of pushbuttons 55, 56. In order that the carbon-pile shall not be sluggish in action at low basic speeds of the motor 10 and erratic at high basic speeds, its action is modified by displacement of the fulcrum 84 of a lever 83 mechanically associating the device 62 with the carbon pile. This displacement is proportional to the movement of the rheostat 42 and is effected by transmitter and receiver devices 89, 88. The devices 57, 59, 88, 89 are energized from a single-phase supply 66, and current for the motor and generator fields is derived from an exciter 29.